Abstract
To control underwater vehicles appendages such as rudders or fins are generally used. These appendages induce added resistance and deteriorate the quality of the inflow to aft control surfaces or propeller, due to the formation of amongst others horseshoe vortices.In this paper, CFD is used to study the flow around a typical wing-body junction and to obtain insight in how to suppress the horseshoe vortex. For a generic submarine the impact of a range of modifications of the sail on resistance, propulsion and wake field is investigated. Design guidelines regarding the most promising modifications will be given. It will be shown that quite significant improvements of the resistance as well as the wake quality can be obtained by properly designing the junction between the appendage and the hull.